Detectives investigating the gangland murder of Clarence Edwards outside a Manchester nightclub urged the city to break down its 'wall of silence'.

Father of one Clarence Edwards, 26, who ran with one of Manchester's most infamous crime gangs was knifed to death after a 3am row during a friend's birthday party on Saturday – just months after being freed from jail over the fatal stabbing of a man on Christmas Day 2011.

Police have arrested four suspects over Edwards' murder but two have been freed on bail amid fears dozens of key eyewitnesses may be too terrified to come forward. It is thought the motive for Edwards' murder was a revenge attack linked to a feud between rival gangs.

Today, Ch Supt Wasim Chaudhry of Greater Manchester Police said: “We believe at the time there were a lot of people present and a large amount of people who will have seen what has taken place and know who is responsible – yet at the moment there seems to be a wall of silence.

“Clearly this is a very traumatic incident, people may be frightened or worried their names may be mentioned in public or a fear of reprisals.

“We want to reassure the public we have a team of specialist detectives who know how to deal with these kinds of sensitive issues, and that you can come to us in confidence.”

Edwards, from Gorton, who was nicknamed 'Clay', was one of 12 men who stood trial in 2013 after John Lee Barrett, 31, a nephew of of ex-boxing champion Pat Barrett, was stabbed to death by a gangland lynch mob because he accidentally bumped into one of them at a fashion show.

Barrett, a father of two, was set upon by thugs who gatecrashed the event and began behaving 'like a pack of wolves' after they became angry at him colliding with a man in a function room at a club in Rochdale.

During the ferocious assault, the victim, a convicted drug dealer, was battered with bottles, pint glasses, and free standing poles weighing 7.5kg each – which were holding up rope in the VIP area – before he was stabbed in the chest.

Barrett, whose uncle was undefeated as British and European light-welterweight champion in the 1990s, was taken to hospital but died two days later.

Boxer Pat who once trained with Sugar Ray Leonard and was nicknamed 'The Black Flash' was also at the event and was seriously injured as he battled to protect his nephew.

Six men stood trial for murder but were convicted of an alternative charge of attempting to cause grievous bodily harm after it could not be established who killed Barrett.

Edwards, who was thought to be a member of the Moss Side Bloods, affiliated to the notorious Doddington Gang, was one of a further six suspects arrested but not charged with murder.

He later pleaded guilty to violent disorder and was jailed for 30 months in March 2013 and it is thought he was freed in mid-2014. All 12 suspects were jailed for a total of 98 years over the attack.

Edwards was stabbed after he attended a private party at the R-Base club in Manchester. Emergency services were called to reports of a disturbance in Charles Street at 3.25am, and arrived to find Edwards lying on the ground surrounded by a group of people.

Police and paramedics tried to revive him at the scene and rushed him to hospital but he died a short time later.

No weapon has been recovered at this stage and it is unclear whether the weapon was brought into the club or to the street outside.

A 26-year-old man and a 37-year-old man were arrested but later freed on police bail. Two other men aged 22 and 26 are still in custody on suspicion of murder.

Mr Chaudhry added: “We are aware there is speculation that this could have been linked to a previous incident, but at the moment we are keeping all lines of inquiry open. Clarence was well known in the community.

''He was a father, a cousin, a son. He was attending a birthday party and a result of that he has been murdered. This is devastating for the family. We will pursue relentlessly all lines of inquiries until we get to the truth.”